A milling machine is a main equipment for maintenance and construction of asphalt road surface, and it is mainly used for excavation and renovation of the asphalt concrete surface of highways, urban roads, airports, freight yard and so on, while it can also be used to clear the defects of swelling, oil waves, texture, rut and other defects on the road. The milling machine mainly includes a walking system, a milling device, a frame and a material conveyor. The material conveyor mainly comprises a first conveying section and a second conveying section. When transporting the material conveyor, the material conveyor is generally designed to be foldable in order to reduce the transportation size. When the material conveyor is in operation, the material conveyor is unfolded (i.e., the second conveying section is unfolded), while when transporting the milling machine, the material conveyor is folded (i.e., the second conveying section is folded) to reduce the transportation size. It is necessary to lock the second conveying section after the second conveying section is unfolded or folded. In the prior art, the locking of the second conveying section is generally carried out in the following three ways:
The first way is: as shown in FIGS. 1 and 2, the second conveying section 102 is fixed with the first conveying section 103 by inserting a pin 101 manually or other means after the material conveyor is folded or unfolded. This way is time-consuming, labor-intensive, inefficient, and requires at least one person to do the fixing work near the material conveyor.
The second way is: the pin is controlled by a hydraulic oil cylinder rather than by inserting a pin manually after the material conveyor is unfolded (there is one oil cylinder at each of the two sides of the material conveyor); the fixing is also carried out by inserting a pin manually near the material conveyor or in other ways (e.g. tying the second conveying section to the first conveying section with a belt) after the material conveyor is folded. The disadvantage is: efficiency is relatively low, and when being folded, it is necessary to fix the material conveyor underneath by a person.
The third way is: it is controlled by a hydraulic oil cylinder rather than by inserting a pin manually after the material conveyor is unfolded (there is one oil cylinder at each of two sides of the material conveyor); it is controlled by another set of hydraulic oil cylinder after the material conveyor is folded. The disadvantage is: this way requires four hydraulic oil cylinders, and the cost is relatively high, moreover, the number of hydraulic components is increased, so that the hydraulic piping wiring becomes complex. On the other hand, the increase of the number of the hydraulic oil cylinders lowers the reliability of the system, and even only one of these four hydraulic oil cylinders is out of order, the material conveyor will go out of order.